1. Field of the Invention
The present invention relates to a video playback device for playing back, from a recording medium, a fullband video signal in which a high frequency signal component is folded onto a low frequency signal component and recorded on the recording medium such as a magnetic tape, and more particularly, to a luminance signal decoding circuit for to correctly decoding a luminance signal of full band without any deterioration of picture quality.
2. Description of the Prior Art
A television signal of NTSC or PAL system which is generally used has a frequency band of about 5 MHz, comprises a luminance signal and chrominance signal.
Namely, a typical television signal comprises a luminance signal having a frequency band of about 5 MHz and a chrominance signal having a frequency band of approximately 1 MHz around 3.58 MHz.
However, a normal cassette tape serving as a recording medium has a frequency bandwidth of approximately 3.5 MHz.
Accordingly, existing video recording and playing back devices can only record and playing back luminance signals of 2.5 MHz and chrominance signals of 1 MHz frequency bands.
Thus, in order to solve a disadvantage of the existing video recording and playing back devices which is not capable of recording a luminance signal of full band to a normal cassette tape, a method capable of recording and playing back a television signal of full band to a normal cassette tape was disclosed in the U.S. patent application Ser. No. 07/569029 filed by Sam Sung Electronic Co. Ltd now U.S. Pat. No. 5,223,262.
In accordance with the aforementioned U.S. patent application Ser. No. 07/569029, the high frequency luminance signal component is folded onto the low frequency luminance signal component during recording, and the high frequency luminance signal folded onto the low frequency luminance signal is then unfolded so as to be distributed to an original frequency band during play back.
The video recording and play back device disclosed in the above-described U.S. patent application Ser. No. 07/569029 provided for the recordation of a motional signal representing image motion together with the chrominance signal in order to control transitions between image regions of the luminance signal upon playing back.
However, the video recording and playing back device described in the above-described U.S. patent application Ser. No. 07/569029 will not correctly reproduce the motional signal when a video playback head could not correctly scan a video track of the tape during playing back, and could not correctly control the transition between regions of the luminance signal because to the motional signal contains errors.
Therefore, the video recording and playing back device described in the U.S. patent application Ser. No. 07/569029 has the a problem that the luminance signal in which the high frequency luminance signal is folded onto the low frequency luminance signal can not be correctly restored causing the image deterioration during playing back.